<div class="panel panel-primary">
  <div class="panel-heading">演示模板内部的局部变量</div>
  <div class="panel-body">
    <input #heroInput>
    <p>{{heroInput.value}}</p>
    <button class="btn btn-success" (click)="sayHello(heroInput.value)">局部变量</button>
  </div>
</div>